Mercruiser 3.0 Pre-Alpha Temperature Sender Question

CableGuy1978

Seaman
Joined
Jul 13, 2010
Messages
66
Hello all!

I am looking for a replacement temperature sender. Last year I noticed after first running the boat fir the year, the temperature gauge climbed to it's normal mark, and then kept climbing past that. I shut it down and let it cool off, and tried it again, it did the same thing. I found out that it wasn't reading correctly as every time now, it goes straight to max. The engine itself is staying cool as I can touch most parts including the exhaust and actually rest my hand on it without burning it. I have also rebuilt the water pump as well, so there is no question that things are staying cool. However, I still would rather have a working temp gauge, saves opening the dog house periodically to touch the engine! :)

I have checked out the gauge itself by grounding out the wire from the sender and it maxes out every time. So at this point, I am looking for a replacement sender.

From searching for them, I have noticed that there are at least 2 different thread types18 NPT, and 14 NPT... Is there only 1 kind of thread type used on older Mercruisers in the pre-alpha range? Serial numbers aren't something that is easy to come by on this Frankenstein boat. Can I get this sender from an auto parts store, or are they Mercruiser specific?

Thank you folks for any help!
 

Silly Seville

Senior Chief Petty Officer
Joined
Dec 5, 2009
Messages
798
Re: Mercruiser 3.0 Pre-Alpha Temperature Sender Question

To my delight, I have found that NAPA is a great resource for parts like this, and they often stock them. Just be sure to take yours with you to match it up.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,149
Re: Mercruiser 3.0 Pre-Alpha Temperature Sender Question

Hello all!

I am looking for a replacement temperature sender. Last year I noticed after first running the boat fir the year, the temperature gauge climbed to it's normal mark, and then kept climbing past that. I shut it down and let it cool off, and tried it again, it did the same thing. I found out that it wasn't reading correctly as every time now, it goes straight to max. The engine itself is staying cool as I can touch most parts including the exhaust and actually rest my hand on it without burning it. I have also rebuilt the water pump as well, so there is no question that things are staying cool. However, I still would rather have a working temp gauge, saves opening the dog house periodically to touch the engine! :)

I have checked out the gauge itself by grounding out the wire from the sender and it maxes out every time. So at this point, I am looking for a replacement sender.

From searching for them, I have noticed that there are at least 2 different thread types18 NPT, and 14 NPT... Is there only 1 kind of thread type used on older Mercruisers in the pre-alpha range? Serial numbers aren't something that is easy to come by on this Frankenstein boat. Can I get this sender from an auto parts store, or are they Mercruiser specific?

Thank you folks for any help!

Ayuh,... About what Vintage motor We talkin' 'bout anyways,..??
 

CableGuy1978

Seaman
Joined
Jul 13, 2010
Messages
66
Re: Mercruiser 3.0 Pre-Alpha Temperature Sender Question

It's a GM 4 cyl, but have yet to actually find a serial number on the engine. We do have a NAPA parts stores everywhere in my area, and I do have the old sender removed so I can take it in to get matched.

Thank you once again for helping me out!
 
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